Dire warming warning for Earth's species
25% could vanish by 2050 as planet heats up, study says

Jane Kay, Chronicle Environment Writer
Thursday, January 8, 2004

More than 1 million plant and animal species will vanish if global temperatures continue to rise as predicted in the next 50 years, scientists say in the first authoritative attempt to gauge the impact of climate change on wildlife. Even small fluctuations in climate can affect a species' ability to remain in its original habitat and survive, according to a study published Wednesday in the British journal Nature. Authors estimate that about a quarter of the estimated 5 million or more land species on the planet may lose habitat and face extinction as they seek cooler temperatures to survive, either by moving to higher ground or away from the equator and closer to the poles.

The key problem, said co-author Lee Hannah, a biologist at the Center for Applied Biodiversity Science at Conservation International in Washington, D.C., is that vulnerable species have no escape routes as temperatures rise. "Slight increases in temperature can force (a species) to move toward its preferred, usually cooler, climate range. If development and habitat destruction have already altered those habitats, the species often have no safe haven,'' he said. The researchers examined impacts on flora and fauna of three scenarios of climate change between now and 2050, ranging from an average annual temperature increase of about 1.4 to 3.6 degrees Fahrenheit. The midrange prediction shows temperatures increasing by about 3 degrees. Under that scenario, said lead author Chris Thomas, a biologist at the University of Leeds (England), about 1.25 million species, or 24 percent of the terrestrial species of plants and animals, will be extinct or on the way to extinction in 50 years. Results were drawn from studies of 1,103 animal and plant species in Mexico, Australia, Europe, the Amazon, the Brazilian Cerrado and South Africa, representing 20 percent of the Earth's landmass. Researchers estimated that 15 to 37 percent of those species could go extinct or be on the path toward extinction by 2050, depending on which of the three climate assumptions is used. The researchers extrapolated the results to make global estimates.

Computer models used to complete the analysis took into account the ability of different species to move under pressure and the current state of their habitat. Some findings are as follows:
- Using the most conservative estimate of global temperature increases of 1.4 degrees Fahrenheit, 18 percent of species would be lost or "committed to eventual extinction.'' In the dry forest of the Brazilian Cerrado, 66 percent of the plants would be facing extinction.
- Under the midrange prediction, 24 percent of species would be lost. Nearly 70 percent of mammals in South Africa that cannot readily move to alternative sites would vanish.
- With a rise of up to 3.6 degrees, 35 percent of species would be lost. In Queensland, Australia, 85 percent of birds would face extinction. In the Amazon, 87 percent of the plants would vanish.

Researchers from 14 institutions around the world cooperated on the study. It began a year ago, when scientists at Leeds, the Royal Society for the Protection of Birds in Bedfordshire, England, and the National Institute of Public Health and Environment in the Netherlands, among others, realized that separate modeling efforts were under way in six regions to discover how global warming might affect species.

In Queensland, the Boyd's forest dragon would have no choice but to move upslope to find its preferred climate. But because the lizard already is found only near mountaintops, it would have nowhere to go.
In South Africa, the toffeeapple conebush, which bears a fruit that looks like a candy apple, is already diminishing from drought and warmer temperatures.
In Europe, the Scottish crossbill, a rare bird, would have to move to Iceland to find a favorable climate, while the red kite, already heavily threatened by hunting and habitat loss, would lose even more territory.
The Oaxacan swallowtail, one of Mexico's rarest butterflies, which was just discovered in 1975 in the Juarez Mountains, could no longer use the natural habitat protected for it under law.

Despite the uncertainties of the modeling, the study authors said, "We believe that the consistent overall conclusions across analyses establish that anthropogenic (human caused) climate warming at least ranks alongside other recognized threats to global biodiversity.'' In many regions, global warming will be the greatest threat, the study said. The authors recommended an immediate reduction of carbon dioxide and other greenhouse gases, which are believed to be the prime cause of global warming. They also advise that conservation measures must be taken to help prepare for the movement by species to survive.

The new study is the latest of several recent reports on global warming, nearly all suggesting a growing consensus that humans are affecting the climate in ways likely to have some devastating impacts on the environment, such as more extreme weather events, earlier spring thaws and flooding along coastlines. Last month, two top U.S. climate researchers released a report that brings near-unanimous agreement that the warming is caused by combustion of fossil fuels and other industrial emissions. They estimate a 90 percent chance that the world's climate will heat up between 3.1 and 8.9 degrees Fahrenheit by the end of this century. Predicted are more heat waves and droughts in some regions and heavy precipitation in others. Wildfires, vegetation changes and continuing melting of glaciers, causing flooding and island inundation are forecast.

President Bush has decided not to sign the Kyoto treaty, an international agreement setting deadlines for reducing greenhouse gas emissions. The administration's chief meteorologist, James Mahoney, assistant secretary of commerce, said last month that he believed that natural variation played as much a part in warming as human-caused activities. He cautioned against dire scenarios based on many differing atmospheric models.

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